The present invention relates generally to a spring-actuated air-brake cylinder as the diaphragm cylinder for vehicle brake systems.
U.S. Pat. No. 5,067,391 describes a spring-actuated air-brake cylinder with diaphragm cylinder wherein there is provided, in the pressure chamber of the spring actuator, a restoring spring that acts on a pressure plate connected by threaded means to a push rod and that presses the diaphragm against a piston plate. Considerable time and effort is needed to assemble this construction, and the spring of the spring actuator must be of relatively heavy design due to the opposing force of the restoring spring.
U.S. Pat. No. 5,507,217 describes a spring-actuated air-brake system with diaphragm cylinder wherein the diaphragm is provided with a central aperture via which the diaphragm can be connected securely to a push rod by means of perforated disks which can be disposed on both sides of the aperture and of a threaded stud which is passed through the perforated disks and screwed into the push rod, so that there is no need for a restoring spring. Relatively large clamping forces are necessary to ensure that the diaphragm is connected in sealed manner to the push rod, and considerable time and effort is required to put the assembly together.
Both of these solutions regarding diaphragm alignment and return have proven less than completely satisfactory. Accordingly, it is desired to provide a new spring-actuated air-brake cylinder as the diaphragm cylinder for vehicle brake systems which overcomes the disadvantages associated with conventional spring-actuated air-brake cylinders with diaphragm cylinders.